Circuit-breaking device for alternating current arranged for the compensation of electro-dynamic forces



p 1965 J. BONNEFOIS ETAL 3,205,333

CIRCUIT-BREAKING DEVICE FOR ALTERNATING CURRENT ARRANGED FOR THE COMPENSATION OF ELECTRO-DYNAMIC FORCES Filed July 11, 1962 2 Sheets-Sheet 1 59- By WW6 Sept. 7, 1965 J. BONNEFOIS ETAL 3,205,333

CIRCUIT-BREAKING DEVICE FOR ALTERNATING CURRENT ARRANGED FOR THE COMPENSATION OF ELECTED-DYNAMIC FORCES Filed July 11, 1962 2 Sheets-Sheet 2 197' 7 DRI E Y United States Patent 3,205,333 CIRCUIT-BREAKING DEVICE FOR ALTERNATING CURRENT ARRANGED FOR THE COMPENSA- TION OF ELECTRO DYNAMIC FORCES Jean Bounefois and Jacques Caillard, Saint-Quentin, France, assignors to Compagnie Generale dElectricite, Paris, France, a French corporation Filed July 11, 1962, Ser. No. 209,168 Claims priority, application France, July 13, 1961, 867,900 12 Claims. (Cl. 200-170) It is well known to utilize the electro-dynamic forces developed by the passage of a fault current for the purpose of reinforcing the pressure at the point of contact of the fixed and movable elements of a circuit-breaker.

In general, in the appliances hitherto constructed, the compensating device for the electro-dynamic forces bears upon the general mechanism that serves for controlling the closing and opening of the apparatus, and all the members of this mechanism, as well as the frame, have to be so designed as to be able to resist the substantial forces transmitted.

Since however these appliances do not enable the separation of the contacts to b eifected at will in the neighbourhood of the passage of the fault current to zero value, the wear on the are members is considerable, and the energy developed in the interruption chamber is high.

The present invention relates to the construction of apparatus in which the electro-dynamic forces are used strictly for reinforcing the contact pressure without involving supplementary reactions upon the mechanism, and in which the arrangement does not permit the separation of the contacts except in the neighbourhood of a passage to zero of the fault current.

It concerns a circuit-breaker for interrupting alternating current, so arranged as to compensate for the electrodynamic forces, and characterised by the feature that the stationary contact is double-faced, so as to be gripped between two movable contacts, which are substantially parallel to one another when in a closed position, and are each mounted at the end of a conducting finger pivoting about an axis, these fingers together constituting a gripper, the hinge of which forms the inlet or outlet for current, the two fingers of the gripper being mechanically connected by an articulation subjected to the action of springs in such a manner as to eifect the closing of the gripper even in the absence of current, this closing pressure being reinforced by the electro-dynamic forces due to the passage of the current.

Another object of the invention is to provide circuitbreaker equipped for the interruption of large currents, and comprising also spark-extinguisher or arc-rupturing means constituted by a third finger mounted on a pivot and subjected to contact pressure against that finger of the gripper which opens its contact on release after that of the other finger of the gripper, under the action of a spring mounted upon a rod with an abutment at atfixed point, in such a way that upon release, the spark-extinguishing finger opens its contact after those of the fingers of the interrupting gripper.

The details of the construction and operation of such a circuit-breaker will be clearly understood by means of the description hereunder, referring to the accompanying drawings, showing by way of example of the construction of a circuit-breaker according to the invention.

In these drawings, FIGURE 1 is a diagrammatic view of the switch, equipped with a spark-arresting or arcrupturing finger and assumed to be maintained in the engaged position by a locking member representing the general mechanism.

3,205,333 Patented Sept. 7, 1965 FIGURE 2 is a view of the switch of FIGURE 1 in the released position.

As represented by the drawing, the circuit-breaking gripper constituted by fingers 3 and 4 is mounted between a conductor 20 and a conductor 21. The movable conducting finger 3 is articulated upon a stationary pivot 16, and the movable conducting finger 4 upon a stationary pivot 17. T h double contact provided upon the conductor 20 is denoted by 1 and 2, and at the hinge of the gripper the fingers 3 and 4 are connected to the conductor 21 by a flexible conducting braid 23. A stop 15 is provided for the purpose of limiting the opening movement of the finger 3.

The mechanism connecting the two fingers of the gripper comprises a lever 7, which pivots about a stationary fulcrum 28. One end of this lever is connected to the finger 3 at 24 through the medium of a connecting-rod 14, and its other end is connected to the finger 4 at 25 through the medium of a connecting-rod 26.

As illustrated in FIGURE 1, the finger 3, connected at 30 to an arm 27, is maintained in a closed position by a locking member consisting of a lever 13 pivoting about a stationary fulcrum 18, and a lock of catch 22.

The mechanical pressure upon the contacts is furnished by the three springs 12, 5 and 9, in compression when the general mechanism is maintained in the engaged position by the locking member 22. The spring 12 is mounted at the free end of the arm 27, and is kept in compression by the lever 13 and the locking member 22. This spring can extend, upon release, until a stop 29 comes into contact with the arm 13. The spring 5 is mounted in compression upon the rod 26, and its expansion upon release is limited by the rod 7 coming into contact with an abutment 6 at the end of the rod 26.

The equipment of the switch with a view to the interruption of large currents is constituted by a spark-arresting or arc-rupturing finger 19, articulated about a pivot 31 upon the conductor 20. The finger 4 of the gripper is extended at 32, facing the spark-arresting finger 19, and is subjected, with it, to contact pressure at 8 by the spring 9, mounted in compression upon a rod 33, and bearing against a stationary stop 11, here assumed to be integral with the conductor 20. The expansion of this spring, upon release, is limited by an abutment 10, at the end of the rod 33, coming into contact with the supporting stop 11.

The circuit-breaker that has just been described operates in the following manner:

In the engaged position (FIGURE 1), when the apparatus is being transversed by current, the attracting force, developed by the parallel currents flowing in the same direction through the fingers 3 and 4 of the gripper, occasions, at the level of the points of contact 1 and 2, a pressure additional to that due to the springs. It will be observed that these forces of attraction between the fingers 3 and 4, being equal and in opposite directions, are absorbed by the conductor 20 and the pivots 16 and 17, without creating any supplementary reaction either upon frame or upon the operating mechanism of the apparatus.

In the spark-arresting circuit, on the contrary, there is a repelling force at 8 between the parts 19 and 32, the currents being parallel and in opposite directions.

Now the general conditions of interruption require that the last contact that separates should be the sparkarresting contact 8. Since the electro-dynamic forces act in the closing direction upon the loop of the main circuit of the interrupting gripper and in the opening direction upon the loop of the spark-arresting circuit, it is necessary, at the time of release, to open the main circuit 1 first, in order to counteract the closing forces that are exerted upon the finger 3, and then to utilize 3 the opening forces that are then exerted upon the finger 4 for the purpose of opening the contact 2.

Owing to the arrangement of the parts that enables the various circuits to be constituted while respecting the condition of minimum variation of flux embraced by the circuit before and after the commutation of the fault current from one circuit to another, the commutation of the current from the circuit of the finger 3 to the circuit of the finger 4 and then to the spark-arresting circuit 8 is good, provided the contacts are opened in the following order: main contact 1, then main contact 2, and finally spark-arresting contact 8. In this way it will be possible to effect the separation of the contacts in safety.

Finally, the arrangement of the apparatus is such that the opening of the contacts is effected in the order indicated not only in the case in which the apparatus is being traversed by a large current but also in that in which it is being traversed by a small current, or by no current at all.

In point of fact, in the engaged position, the mechanical pressures that are being exerted upon the contacts are distributed as follows:

Contact 1: the spring 12, bearing upon the lever 13 of the lock-ing means, exerts, through the medium of the arm 27, a closing torque upon the finger, 3, but the spring 5, through the medium of the parts 7 and 14, exerts an opening torque upon this same finger. The difference between these two torques determines the pressure at the level of the contact 1.

Contacts 2 and 8: the values of the pressures on these points of contact are determined by the combination of the forces of the springs 5 and 9.

With an appropriate adjustment of the position of the abutments 6 and 16 upon their individual rods, 26 and 33 the opening movement, in the absence of current or under weak current, then takes place as follows: The lever 13, having received the release command by the opening of the catch 22, comes in its movement into contact with the abutment 29, and then the action ,of the spring 12 ceases. Consequently the opening torque exerted by the spring 5 upon the finger 3 acts, the contact 1 opens, and the finger 3 carries along the mechanism connecting the fingers of the gripper. The arm 7 coming into contact with the abutment 6, the latter then opens the contact 2. As soon as the displacement of the finger 4 is sufiicient the abutment 10 occasions the opening of the sparl -arresti-ng contact 8. The opening movement of the apparatus proceeds until the finger 3 rests upon the stop (FIGURE 2).

Under a substantial current the procedure is different, owing to the combined action of the springs and the electro-dynamic forces.

As soon as the release command is transmitted to the apparatus, and the action of the spring 12 ceases, as before, the finger 3 is then subjected to the following oppositely directed forces:

in the opening direction, to the force of the spring 5:

in the closing direction, to the resultant of the forces created in the interior of the compensating device by the fault current.

There therefore exists a position of equilibrium, and the apparatus will be designed, within the ambit of the invention, in such a way that this equilibrium will be produced for a low instantaneous value of the fault current. For this it is suificient to adjust the springs as a function of the dimensioning of the apparatus, and particularly of the inter-axial distance 16, 17.

Above this value, the electro-dynamic forces that tend to close the apparatus are greater than the constant mechanical forces that act in the opening direction. When the current diminishes to an instantaneous value lower than the equilibrium value, that is to say, into the neighbourhood of a passage to zero of the fault current, the finger 3 can begin its movement for opening the contact 1. The fraction of the current passing through this finger is then commuted upon the finger 4, which serves as the sole conductor of the entire current. Since the compensatory effect due to the gripper no longer exists, all the forces that are exerted upon the finger 4 contribute to the opening, which is necessarily produced in the order of the contact 2 first and then the contact 8.

We claim:

1. An alternating current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as the input and output circuits, respectively, for said circuit-breaker, one of said conductors being provided wit-h a double-faced stationary contact arranged to be gripped between two movable contacts each being mounted at the end of a conducting finger pivotable about a separate parallel axis, said fingers being essentially parallel in the closed position and pivotable about their respective axes to form an angle in the open position, spring means for releasably maintaining said fingers in the closed position, and locking means for releasing said spring means to free said fingers for movement to the open position, said fingers being connected in parallel in their closed position between said first and second conductor means so that said fingers will remain for a time in the closed position upon the release of said spring means due to the electro-dynamic forces of said fault current.

2. An alternating current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as the input and output circuits, respectively, for said circuit-breaker, one of said conductors being provided with a double-faced stationary contact arranged to be gripped between two movable contacts each being mounted at the end of a conducting finger pivotable about a separate parallel axis, said fingers being essentially parallel in the closed position and pivotable about their respective axes to form an angle in the open position, spring means for releasably maintaining said fingers in the closed position, and locking means for releasing said spring means to free said fingers for movement to the open position, said fingers being connected in parallel in their closed position between said first and second conductor means so that said fingers will remain for a time in the closed position upon the release of said spring means due to the electro-dynamic forces of said fault current, said spring means including an articulation constituted by a combination of connecting rods and levers, said articulation being connected at one end to one of said fingers and having its other end supported on a first spring connected to the other finger, said articulation being maintained in a state of equilibrium when said circuit-breaker is in the closed position with current applied thereto by the resultant force of said first spring, said locking means and said electro-dynamic forces. 7

3. An alternating current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as the input and output circuits, respectively, for said circuit-breaker, one of said conductors bemg provided With a double-faced stationary contact arranged to be gripped between two movable contacts each being mounted at the end of a conducting finger pivotable about a separate parallel axis, said fingers being essentially parallel in the closed position and pivotable about their respective axes to form an angle in the open position, spring means for releasably maintaining said fingers in the closed position, and locking means for releasing said spring means to free said fingers for movement to the open position, said fingers being connected in parallel in their closed position between said first and second conductor means so that said fingers will remain for a time in the closed position upon the release of said spring means due to the electro-dynamic forces of said fault current, said spring means including an articulation constituted by a combination of connecting rods and levers, said articulation being connected at one end to one of said fingers and having its other end supported on a first spring connected to the other finger, said articulation being maintained in a state of equilibrium when said circult-breaker is in the closed position with current applied thereto by the resultant force of said first spring, said locking means and said electro-dynamic forces, a second spring associated with said locking means cooperating With said first spring in the absence of current applied to said circuit-breaker and when said locking means is engaged to maintain said articulation in a state if equilibrium with said fingers in the closed position, said first spring being operative to exert contact pressure on said other finger and an opening torque by way of said articulation on said one finger, and said second spring being operative when said locking means is engaged to exert a closing torque on said one finger of greater magnitude than the torque applied thereto by said first spring.

4. A circuit-breakerKas defined in claim 3 and further comprising first abutment means associated with said second spring for rendering said second spring inoperative upon release of said locking means and second abutment means associated with said first spring for rendering said first spring inoperative after said electro-dynamic forces have been reduced below the level of said opening torque and upon movement of said first finger to the open position, permitting said other finger thereafter to move to the open position.

5. An alternating current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as the input and output circuits, respectively, for said circuit-breaker, one of said conductors being provided with a double-faced stationary contact arranged to be gripped'between twomovable contacts each being mounted at the endof a conducting finger pivotable about a separate parallel axis, said fingers being essentially parallel in the closed position and pivotable about their respective axes to form an angle in the open position, spring means for releasably maintaining said fingers in the closed position, and locking means for releasing said spring means to free said fingers for movement to the open position, said fingers being connected in parallel in their closed position between said first and second conductor means so that said fingers will remain for a time in the closed position upon the release of said spring means due to the electro-dynamic forces of said fault current, spark arrestor means associated with said one conductor means in operative relationship with one of said fingers, said spark arrestor means including adidtional spring means for applying an opening torque to said one finger in opposition to said spring means.

6. An alternating current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as the input and output circuits, respectively, for said circuit-breaker, one of said conductors being provided with a double-faced stationary contact arranged to be gripped between two movable contacts each being mounted at the end of a conducting finger pivotable about a separate parallel axis, said fingers being essentially parallel in the closed position and pivotable about their respective axes to form an angle in the open position, spring means for releasably maintaining said fingers in the closed position, and locking means for releasing said spring means to free said fingers for movement to the open position, said fingers being connected in parallel in their closed position between said first and second conductor means so that said fingers will remain for a time in the closed position upon the release of said spring means due to the electro-dynamic forces of said fault current, said spring means including an articulation constituted by a combination of connecting rods and levers, said articulation being connected at one end to one of said fingers and having its other end supported on a first spring connected to the other finger, said articulation being maintained in a state of equilibrium when said circuit-breaker is in the closed position wth current applied therto by the resultant force of said firstspring, said locking means and said electro-dynamic forces, a second spring associated with said locking means cooperating with said first spring in the absence of current applied to said circuit-breaker and when said locking means is engaged to maintain said articulation in a state of equilibrium with said fingers in the closed position, said first spring being operative to exert contact pressure on said other finger and an opening torque by way of said articulation on said one finger, and said second spring being operative when said locking means is engaged to exert a closing torque on said one finger of greater magnitude than the torque applied thereto by said first spring, spark arrestor means including an additional finger pivotable about an axis connected to said one conductor means, additional spring means for applying an opening torque to said other finger via said additional finger which is operative to force said other finger to the open position after said one finger has moved to the open position.

7. A circuit-breaker as defined in claim 6 wherein said first spring, said additional spring means and said articulation are so arranged with respect to said fingers that the forces transmitted thereby under all conditions of operation of said circuit-breaker provide for first opening said one finger, then opening said second finger and finally opening said additional finger of said spark arrestor means.

8. An alternating current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as the input and outputcircuits, respectively, for said circuit-breaker, one of said conductors being provided with a double-faced stationary contact arranged to be gripped between two movable contacts each being mounted at the end of a conducting finger pivotable about a separate parallel axis, said fingers being essentially parallel in the closed position and pivotable about their respective axes to form an angle in the open position, spring means for releasably maintaining said fingers in the closed position, and locking means for releasing said spring means to free said fingers for movement to the open position, said fingers being connected in parallel in their closed position between said first and second conductor means so that said fingers will remain for a time in the closed position upon the release of aid spring means due to the electro-dynamic forces of said fault current, said spring means including an articulation constituted by a combination of connecting rods and levers, said articulation being connected at one end to one of said fingers and having its other end supported on a first spring connected to the other finger, said articulation being maintained in a state of equilibrium when said circuit-breaker is in the closed position with current applied thereto by the resultant force of said first spring, said locking means and said electro-dynamic forces, a second spring associated with said locking means cooperating with said first spring in the absence of current applied to said circuit-breaker and when said locking means is engaged to maintain said articulation in a state of equilibrium with said fingers in the closed position, said first spring being operative to exert contact pressure on said other finger and an opening torque by way of said articulation on said one finger, and said second spring being operative when said locking means is engaged to exert a closing torque on said one finger of greater magnitude than the torque applied thereto by said first spring, said one end of said articulation being connected to one of said fingers at a point of said finger in the vicinity of the pivot axis thereof, the distance of said point to said pivot axis determining the resultant force on said one finger in favor of the electro-dynamic force produced by the passage of a fault current of at least minimum magnitude through the parallel circuit arrangementof said fingers over said opening torque applied to said one finger by said first spring acting through said articulation.

9. An alternating current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as'the input and output circuits, respective ly, for aid circuit-breaker, first and second movable contact means pivotable about separate parallel axes and in gripping contact with one of said conductor means in said closed position, spring means for pivoting said movable contact means about their respective axes in opposite directions to said open position, said movable contact means I being connected between said first and second conductor means so as to maintained in the closed position in the presence of applied current of at least minimum magnitude by the electro-dynamic forces generated by said current in spite of opposing forces applied by said spring means.

10. An alternating current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as the input and output circuits, respectively, for said circuit-breaker, first and second movable contact means pivotable about separate parallel axes and in gripping contact with one of said conductor means in said closed position, spring means for pivoting said movable contact means about their respective axes in opposite directions to said open position, said movable contact means being connected between said first and second conductor means so as to be maintained in the closed position in the presence of applied current of at least minimum magnitude by the electro-dynamic forces generated by said current in spite of opposing forces applied by said spring means and, locking means for releasably maintaining said first and second movable contact means in the closed position in the absence of applied current to said circuitbreaker.

11. An alternating current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as the input and output circuits, respectively, for said circuit-breaker, first and second movable contact means pivotable about separate parallel axes and in gripping contact with one of said conductor means in said closed poistion, spring means for pivoting said movable contact means about their respective axes in 0pposite directions to said open position, said movable contact means being connected between said first and second conductor means so as to be maintained in the closed position in the presence of applied current of at least minimum magnitude by the electro-dynamic forces generated by said current in spite of opposing forces applied by said spring means, said spring means further including articulation means connected between said first and second movable contact means for effecting in the absence of a minimum current applied to said circuit-breaker the pivoting of said first movable contact means prior to said second movable contact means.

12. An alternatiing current circuit-breaker for opening a circuit in response to a fault current having an open and closed position comprising first and second conductor means serving as the input and output circuits, respectively, for said circuit-breaker, first and second movable contact means pivotable about separate parallel axes and in gripping contact with one of said conductor means in said closed position, spring means for pivoting said movable contact means about their respective axes in opposite directions to said open position, said movable contact means being connected between said first and second conductor means soas to be maintained in the closed position in the presence of applied current of at least minimum magnitude by the electro-dynamic forces generated by said current in spite of opposing forces applied by said spring means and, thirdcontact means mounted on a pivot in connection with said one conductor means and including means for applying a pressure on said second movable contact means effective to pivot said second movable contact means to the open position only after said first movable contact means has been pivoted by said spring means.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A. GILHEANY, Primary Examiner. 

9. AN ALTERNATING CURRENT CIRCUIT-BREAKER FOR OPENING A CIRCUIT IN RESPONSE TO A FAULT CURRENT HAVING AN OPEN AND CLOSED POSITION COMPRISING FIRST AND SECOND CONDUCTOR MEANS SERVING AS THE INPUT AND OUTPUT CIRCUITS, RESPECTIVELY, FOR SAID CIRCUIT-BREAKER, FIRST AND SECOND MOVABLE CONTACT MEANS PIVOTABLE ABOUT SEPARATE PARALLEL AXIES AND IN GRIPPING CONTACT WITH ONE OF SAID CONDUCTOR MEANS IN SAID CLOSED POSITION, SPRING MEANS FOR PIVOTING SAID MOVABLE CONTACT MEANS ABOUT THEIR RESPECTIVE AXES IN OPPOSITE DIRECTIONS TO SAID OPEN POSITION, SAID MOVABLE CONTACT MEANS BEING CONNECTED BETWEEN SAID FIRST AND SECOND CONDUCTOR MEANS SO AS TO MAINTAINED IN THE CLOSED POSITION IN THE PRESENCE OF APPLIED CURRENT OF AT LEAST MINIMUM MAGNITUDE BY THE ELECTRO-DYNAMIC FORCES GENERATED BY SAID CURRENT IN SPITE OF OPPOSING FORCES APPLIED BY SAID SPRING MEANS. 